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New Evidence for an Apple a Day

The old adage promoting an apple a day for better health just got a boost from science. A large Dutch study has found that eating apples and pears is associated with a lower risk of stroke.

The findings counter the widespread belief that the most healthful fruits and vegetables are those that come in deep, rich colors inside and out. The dark green of spinach and deep red of raspberries are produced by phytochemicals that are associated with better heart health and lower rates of cancer, prompting the common advice to “eat your colors.” Apples and pears, although red, light green or yellow on the outside, are typically considered “white” fruits because the inside of the fruit, which represents the largest edible portion, is white.

Researchers in the Netherlands decided to track fruit and vegetable intake based on the color of the largest edible portion of the food. The categories were green (broccoli, kale, spinach and lettuce), orange/yellow (oranges, carrots and peaches), red/purple (cherries, grapes, beets and tomatoes) and white (apples, pears, bananas and cauliflower).

The investigators analyzed data collected from 20,069 men and women who took part in the Dutch Morgen study, which stands for Monitoring Project on Risk Factors and Chronic Diseases. All the participants, ages 20 to 65, were healthy and free of cardiovascular disease at the start. The study subjects filled out food questionnaires detailing their eating habits.

During the next 10 years, the investigators documented 233 strokes among the study participants. There was no relationship between stroke risk and consumption of any of the brightly colored fruits and vegetables. However, people who consumed at least 171 grams of white produce daily — equal to about one medium to large apple — had a 52 percent lower risk of stroke than those who ate less than 78 grams of white fruit a day. On average, every 25 grams of white fruit eaten daily was associated with a 9 percent lower risk for stroke.

The findings were published on Thursday in Stroke: Journal of the American Heart Association.

Although the white category contained a number of foods, the investigators found that apples, pears and applesauce were the most common foods eaten in that category. When analyzed separately, apples and pears accounted for a 7 percent decline in stroke risk for every 25 grams eaten each day.

The strength of the research is that it analyzed a large, population-based study group. The downside is that eating habits were based on people’s own recollections of fruit and vegetable consumption, so the data may not be reliable. For instance, vegetables like onions or peppers that are often chopped and mixed in with foods are not as easy to remember when a person is filling out a dietary questionnaire, so it may be that those foods are underrepresented compared with apples, which are relatively easy to remember eating.

Why apples and pears might reduce stroke risk isn’t known, though both fruits are rich sources of dietary fiber, which is associated with lowering blood pressure. Both fruits also contain a number of nutrients and phytochemicals, including the flavonol quercetin, which may have anti-inflammatory properties.

The investigators noted that the findings should be replicated in other large studies before specific recommendations are made about consumption of white fruits.

“Previous prospective cohort studies found that high fruit and vegetable consumption lowers the risk of stroke,” Linda Oude Griep of the division of human nutrition at Wageningen University said in an e-mail. “This is the first study on color groups of fruits and vegetables and stroke, so yes, these results were surprising. However, these findings need to be confirmed in more prospective cohort studies before definite conclusions can be made.”

The study was financed by several Dutch and European public health agencies, although a portion of the cost was paid by an unrestricted grant from the Dutch Product Board for Horticulture, which promotes agricultural interests in the region.